Hong Kong officials hang their heads for a moment of silence. They are mourning the victims killed when two ferries collided Monday night. Among them -- five children. The police commissioner announced the arrest of six crew members and said more arrests were expected. (SOUNDBITE)(English) COMMISSIONER OF POLICE, TSANG WAI-HUNG, SAYING: "From the investigation so far, we've come to the suspicion that the crew responsible for manning the two vessels has not exercised the care required of them by law to ensure the safety of the vessels that they are navigating, as well as the people on board their vessels. It is on this basis that they've been arrested to assist police enquiry." Nine people were seriously injured and more than 100 hospitalized after a ferry owned by Hong Kong Electric Company carrying passengers on a company outing collided with another ferry and sank. The second ferry owned by Hong Kong and Kowloon Ferry Holdings made it safely to the pier. Rescuers are still searching for those missing, but an official said early efforts were hampered by the vessel being partially sunken as well as poor visibility and clutter on board. Serious marine incidents are rare in the busy shipping hub.